This invention relates to a locking means for a clamp.
It is known to use clamping devices, for example, grapples, to hold a load while it is lifted and carried from one place to another with the assistance of an overhead cable or the like. The cable may or may not form part of a crane, gantry, etc. It is desirable to have a simple locking arrangement which enables the jaws of the clamp to be held in a desired disposition, at least momentarily, while the clamp is in use. It is, accordingly, an object of the present invention to go at least some ways towards achieving this, or to at least provide the public with a useful choice.
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According to one aspect of the invention, there is provided locking means, the locking means comprising a catch portion and a guide portion, the catch portion and the guide portion being capable of movement with respect to one another, the catch portion having a rider, and the guide portion having a pathway for guiding the rider;
the locking means forming part of or being associated with clamping means, wherein the clamping means has a first jaw and a second jaw, the locking means being arranged such that the catch portion can move in a first direction with respect to the guide portion such that the rider moves along the pathway until it reaches a stepped portion of the pathway, the arrangement being such that when the rider is in a certain position in the stepped portion the jaws are unable to close with respect to one another, and wherein the rider can then be moved from the stepped portion and in a second direction to enable the jaws to close with respect to one another.
Preferably, the first and second directions are substantially opposite with respect to one another.
Preferably, the guide portion includes a block, and the pathway comprises a series of channels within the block, each channel being at a different level.
Preferably, each channel is separated from the other channels.
Preferably, the series of channels comprises a first channel, a second channel angled away from the first channel, a third channel angled away from the second channel, and a fourth channel angled away from the third channel; the channels being such that the rider can move along the first channel, then into the second channel, then into the third channel, and then into the fourth channel.
Preferably, the second and third channels together form the stepped portion.
Preferably the rider forms part of a spring tensioned rod, for example a small part of the rod turned at an angle (eg a right angle) with respect to the rest of the rod.
Preferably, the catch portion includes a sleeve which can move around the guide portion.
Preferably, the catch portion is connected to the jaws by way of lengths of chain or cord.
Preferably, the jaws can pivot with respect to the guide portion.
According to a further aspect of the invention, there is provided a clamp, comprising a sleeve, a shaft, a pair of jaws, a rod, a long line attachment, a first channel, a second channel, a third channel, and a fourth channel;
a first end of the sleeve being combined with the long line attachment, and a second end of the sleeve receiving the shaft, the sleeve being moveable longitudinally around the shaft, the rod having an angled rider part arranged such that when the sleeve is moved downwards on the shaft the rider can be received in and move along the first channel, and then at an angle to the first channel into the second channel, and then to the third channels and will remain at a locked position in the third channel until forcibly moved along the third channel, and then at an angle into the fourth channel to unlock the jaws so that they can move towards one another in a clamping action. Optionally, the rod is spring tensioned. Optionally, the second and third channels are angled with respect to one another. Optionally, the first, second, third, and fourth channels are in a block associated with the shaft, and each channel is at a different level in the block.